Using a flash of a device with the possibility to record light data, e.g. a flash of a digital camera, video recording device or a IR camera, can be troublesome as quite often the target, i.e. an object or part of a scene in front of the device which the user of the device intends to e.g. take a photo of, is out of reach of the flash or the flash illuminates the target and its surroundings in a disadvantageous way.
In some devices, a typical flash solution is a LED flash with some sort of lens in front of the LED. The lens solution can be everything from a plastic window to a total inner reflection (TIR) Fresnel lens. Such a flash solution 200 is shown in FIG. 2. The flash 200 comprises a light source 206 emitting light 208, for example a LED light source. The flash 200 further comprises a TIR element 204 for guiding the emitted light 208 (with minimum light loss due to the TIR property of the TIR element 204) into a Fresnel lens 202.
For any type of lens to be used in a flash, a few important parameters needs to be taken into consideration, e.g. what uniformity of illumination is required, what lens gain is desired and what is the factory tolerances. The lens gain is a value that describes how much the lens will collect the light compared to a using a bare LED without a lens. A lens with a high lens gain thus provides a light cone from the flash which reaches far but only illuminates a small portion of the scene in front of the device.
A solution to the problem of not illuminating the target with the flash when e.g. taking a picture with the device may be to use a Xenon flash, but this requires high voltage and space, which often not is provided by compact devices such as a camera in a mobile phone. Another solution may be to use a high power LED with super capacitors to be able to feed the LED with higher current, which also is an unsuitable solution for compact devices such as a camera in a mobile phone.
Moreover, depending on the scene which a user of the device intends to capture, using different light cones may be advantageous. This may not be possible using a lens arrangement as described above and shown in FIG. 2.
It is within this context that embodiments of the invention arise.